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Abstract According to the topographical，geological features，the distribution of weak structural，shallow relaxation unloading phenomena and reinforcement program of Xiaowan high arch dam，the 3D geomechanical model is set up；and a kind of model test material called temperature analogous material whose strength varies with temperature in the process of experiment is developed to simulate the decrease of the major weak structural planes. Then，the failure test is carried out by comprehensive method which considering both overloading and strength-decreasing. Through the test，the deformation characters of dam foundation and abutment，the failure process，modes and mechanism are obtained. The safety evaluation of model experiment indicates that the strength margin coefficient is 1.2 and the overloading coefficient is 3.3–3.5；and the global factor of safety for the dam foundation and abutment is 3.96–4.20. Synthetical analysis of test data indicates that the displacement，failure status and zone of mid-upper abutment are relatively less due to the excellent reinforcement effects of concrete displacement plugs on faults and alteration zones. Based on the failure status and zone in the model test，some suggestions are proposed that the faults F11 and F10 above the elevation of 1 245 m in the right abutment and the rock above the thrust block in the left abutment should be reinforced.
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Received: 14 May 2010
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2010, Vol. 29 
